Many microbial organisms can have their pathogenic potential inhibited by exposure to ultraviolet light. The organisms vary in susceptibility to this germicidal light. Therefore, in order to kill a number of different organisms, a minimum dose of ultraviolet light must be delivered, which corresonds to the minimum killing dose for the most resistant organism.
Ultraviolet light can be produced by several different mechanisms. The most common source of this light for germicidal use is a mercury arc discharge lamp. The ultraviolet output of mercury arc discharge lamps is a function of several factors, including the age of the lamp, the current at which the lamp is operated and the lamp temperature.
Since a germicidal system based on ultraviolet light requires a minimum dose and since the source of this light is subject to intrinsic variations, it is necessary to utilize a dose monitor in an ultraviolet light type germicidal system.
It is important, however, that the dose monitor be substantially independent of temperature variations, so that the germicidal system can be used under various temperature conditions. A prior art dose monitor is disclosed in Adler U.S. Pat. No. 4,010,372. However, the Adler system is sensitive to temperature variations which can produce inaccurate results.
We have discovered a temperature independent process and device for measuring the amount of irradiation of a predetermined frequency, which process and device is useful in connection with ultraviolet light type germicidal systems. It is to be understood, however, that our process and device is not limited to ultraviolet light type germicidal systems, as our process and device may be used for measuring the amount of irradiation of other frequencies.